Large diameter earth boring bit

ABSTRACT

The rolling cutters of a large diameter earth boring bit are locked in place in a saddle mount yet may easily be removed. A vee-shaped, slabbed-off portion of the journal is held in place by a cap bolted to the saddle mount.

United States Patent Conn [4s] nee. 12, 1972 [541 LARGE DIAMETER EARTH BORING 2,187,037 1/1940 Kirkpatrick 75/372 x B11" 1,879,034 9/1932 Behnke et al.... ..l75/363 2,049,047 1936 B I ..l 36 [72] inventor: William M. Conn, Dallas, Tex. 7/ ee 75/ 3 [73] Assignee: Dresser Industries, Inc., Dallas, Tex. Primary Exami"e"David Brown Attorney-Robert W. Mayer, Thomas P. Hubbard, Jr., Filed! J 1971 Daniel Rubin, Raymond T. Majesko, Roy L. Van Win- [21] AppL NOJ 106,220 kle, William E. Johnson, Jr. and Eddie E. Scott [57] 1 ABSTRACT [2?] $5.3]. "172/2154, 2371543 5 4 The rolling cutters of alarge diameter earth boring bit I I c l H c 1 /0 are locked in place in a saddle mount yet may easily [58] Field of Search 308/82, he removed. A vee shaped slabbed off portion of the l75/361-364, 371, 372,359, 368, 344 journal is held in place by a cap bolted to the saddle V mount. r [56] References Cited 4 Claims, 6 Drawing Figures UNITED STATES PATENTS r 3,612,196 10/1971 Dixon ....l75/364 PATENTED DEC 12 I972 SHEET 1 BF 2 FIG.

FIG. 3 m 4 INVENTOR WILLIAM M. CONN a Zia 1. 2

ATTORNEY PATENTED DEC 12 m2 7 I sum 2 OF 2 FIG. 5

FIG.6

INVENTOR WILLIAM M. CONN lad- ATTORNEY LARGE DIAMETER EARTH BORING BIT BACKGROUND OF THE INVENTION The present invention relates to an improved earth boring bit and more particularly to a removable cutterassembly for an earth boring bit that insures that the cutters will be locked firmly in place during drilling yet allows the cutters to be easily and quickly changed.

The cutter assembly of an earth boring bit must be easy to assembly, must lock firmly in place during operation and must be easy to disassemble. The cutter assembly generally operates under severe conditions and is subject to the corrosive forces of the drilling environment. In addition, the cutter assembly must be adapted to withstand heavy loading and high torque.

The rotatable cutters are positioned between a pair of support arms extending from the body of the bit. A

journal assembly extends between the support arms and secures the cutter to the main bit body. The cutters have a useful lifetime thatis much shorter than the lifetime of the bit. Consequently, meansrnust be provided to allow the cutters to be changed. The heavy loading and high torque encountered during the drilling operation as well as the corrosive drilling environment complicates the problem of providing a cutter that will remain firmly in place during drilling'yet may easily be changed.

DESCRIPTION OF THE PRIOR ART A large diameter earthv boring bit is shown in US. Pat. No. 3,203,492 to C. L. Lichte, patented Aug. 31, 1965. A number of small rotatable cutters are mounted in a multiplicity of saddles positioned on a large diameter earth boring bit. The bit is rotated and the cutters contact and disintegrate the earth formations. The cutters are removable by removing a retaining pin that extends between the arms of the saddles. The retaining SUMMARY OF THE INVENTION The present invention provides a simple and effective means of locking rotatable cutters in the saddles of an earth boring bit. The journal includes a vee-shaped lower portion that will take side loading and torque, and a slabbed-off portion that will take thrust. The journal is secured in place by a cap that is affixed to the saddle. The rotatable cutters may be easily changed yet are held securely in place during operation.

It is therefore an object of the present invention to provide an earth boring bit including rotatable cutters that may be easily and quickly changed.

It is a further object of the present invention to provide a simple and effective journal assembly for locking rotatable cutters on an earth boring bit.

It is a still further object of the present invention to provide a journal assembly for securing rotatable cut- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a large diameter earth boring bit constructed in accordance with the present invention.

FIG. 2 is a side view of one of the journals shown mounted in one arm of the saddle of the earth boring bit shown in FIG. 1.

FIG. 3 is a side view of the journal shown in FIG. 2. FIG. 4 is an end view of the journal shown in FIG. 3. FIG. 5 shows the journal locked in place by a cap. FIG. 6 illustrates another embodiment of the cap shown in FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1, a large diameter earth boring bit is shown generally at 10. A first pair of rotatable cutters 11 and 12 are positioned next to the central shaft 13 and mounted in a pair of saddles I4 and 15. At least two cutters are generally used at a given radius about the central shaft 13 to insure a balanced drilling bit and a smooth drilling operation. Saddles 14 and I5 allow the cutters to be easily removed and new cutters inserted. A second pair of cutters 1'6 and 17 are located below cutters 11 and 12. Cutters 16 and 17 are mounted in a pair of saddles 18 and 19 mounted on the frame of the large diameter bit 10. The upper. end of shaft 13 is threaded to allow the bit to be connected to a rotary drill string (not shown).

The drilling operation generally proceeds by the drilling of a small diameter hole approximately the size of shaft 13. The small diameter hole is drilled to an underground opening and the small diameter bit removed from the drill string. The large diameter bit 10 is then attached to the drill string and rotated and hydraulically raised along the pilot hole thereby enlarging it to the desired size. As bit 10 rotates, cutters l1, 12, 16 and 17 contact and disintegrate the formations. The cutting surfaces of cutters 11, 12, 16 and 17 should traverse the entire surface of the hole being drilled and the saddles and other portions of the bit should not contact the formation.

Difficulty has been encountered adequate bearing support for the rotating cutters of the large diameter bit 10. The bearing must be securely locked in place during drilling and must include means for releasing the cutters from the saddles to allow a change of cutters.

Saddle 18 is shown cut away in FIG. 2 to illustrate journal 20. Journal 20 is positioned in the central annulus of cutter 16 and locked firmly in place, thereby securing cutter 16 in position during the drilling operation. The end of journal 20 is slabbed off forming a pair of surfaces 21 and 22 that are at an angle to the central axis of journal 20. Surfaces 21 and 22 are best shown in the end view of FIG. 4. The surfaces 21 and 22 meet to form a vee-shaped, slabbed-off end portion.

in providing Referring now to FIG. 5, the journal 20 is shown mounted in one arm of saddle 18. A cap 23 is positioned on the arm of saddle 18 and held in place by bolts 24 and 25 locking journal 20 in place. Bolts 24 and 25 are pivotallymounted on cross frames 26 and 27. Cap 23 may be removed by loosening bolts 24 and 25 and pivoting them outward so that they are disengaged from cap 23. Once cap 23 has been removed, journal 20 may be disengaged from saddle 18 and the cutter l6 removed. A new cutter may then be inserted and locked in position by replacing cap 23 and bolts 24 and 25. j

The vee-shaped, slabbed-off portion of journal 20 allows the assembly to take side loading, torque and thrust. The surfaces 21 and 22 allow the assembly to take side loading and torque. Journal 20 is thereby prevented from rotating in saddle '18 and will withstand the high loads applied by the rotational movement of bit 10. Because surfaces 21 and 22 are inclined to the central axis of journal 20, the assembly will withstand high thrust load such as those applied by pull of the drilling machine. As previously explained, the cutters may easily and quickly be changed by removing the caps holding the journals in place.

Referring now to FIG. 6, another embodiment of one of the caps for holding the journals in place is shown. Cap 28 shown in FIG. 6 may be pivoted about hinge element 29. This allows the cap 28 to be displaced by removal of a single bolt. Cap 28 is mounted on the saddle in the same manner as the cap of the previous embodiment. A bolt extends through opening 30 and a pin extends through hinge element 29 to secure cap 28 in place. When the journal is to be removed, the bolt is disengaged and cap 28 is pivoted on hinge element 29.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

I. An earth boring bit comprising:

a main bit body;

at least one pair of support arms extending from said main bit body, at least one of the support arms having a pair of supporting surfaces;

a rolling cutter positioned between said pair of support arms, said rolling cutter having a central annulus;

a joumal'positioned in the central annulus of the rolling cutter and extending between said support arms, said journal including a vee-shaped end portion having a pair of journal surfaces that are at an angle to the central axis of said journal with said pair of journal surfaces adapted to engage said supporting surfaces on said at least one of the support arms; and

a cap removably connected to said one support arm for securing said journal and rolling cutter in position.

2. The earth boring bit of claim 1 wherein said cap is pivotally connected to said one support arm.

3. An apparatus for securing rotatable cutters in the support arms of a saddle of an earth boring head, said apparatus adapted to take side loading, torque and thrust, comprising:

a pair of adjacent supporting surfaces on one of said support arms;

a rolling cutter positioned in said saddle, said rolling cutter havin ,a central annulus; a ournal post ioned in the central annulus of the rolling cutter and extending between said support arms, said journal including a vee-shaped end portion having a pair of journal surfaces that are at an angle to the central axis of said journal with said pair of journal surfaces adapted to engage said supporting surfaces on said support arm; and a cap removably connected to said support arm for securing said journal and rolling cutter in position. 4. The earth boring bit of claim 8 wherein said cap is pivotally connected to said one support arm. 

1. An earth boring bit comprising: a main bit body; at least one pair of support arms extending from said main bit body, at least one of the support arms having a pair of supporting surfaces; a rolling cutter positioned between said pair of support arms, said rolling cutter having a central annulus; a journal positioned in the central annulus of the rolling cutter and extending between said support arms, said journal including a vee-shaped end portion having a pair of journal surfaces that are at an angle to the central axis of said journal with said pair of journal surfaces adapted to engage said supporting surfaces on said at least one of the support arms; and a cap removably connected to said one support arm for securing said journal and rolling cutter in position.
 2. The earth boring bit of claim 1 wherein said cap is pivotally connected to said one support arm.
 3. An apparatus for securing rotatable cutters in the support arms of a saddle of an earth boring head, said apparatus adapted to take side loading, torque and thrust, comprising: a pair of adjacent supporting surfaces on one of said support arms; a rolling cutter positioned in said saddle, said rolling cutter having a central annulus; a journal positioned in the central annulus of the rolling cutter and extending between said support arms, said journal including a vee-shaped end portion having a pair of journal surfaces that are at an angle to the central axis of said journal with said pair of journal surfaces adapted to engage said supporting surfaces on said support arm; and a cap removably connected to said support arm for securing said journal and rolling cutter in position.
 4. The earth boring bit of claim 8 wherein said cap is pivotally connected to said one support arm. 